• Economic and Environmental Geology
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• v.24 no.4
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• pp.363-378
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• 1991

Field and microscopic evidence, XRD,EPMA and chemical data suggest that parent rock of talc ore deposits of Yesan district was originated from ultramafic igneous rock. Parent rock can be divided into serpentinized dunite, serpentinized peridotite, metagabbro, amphibolite and hornblende schist. The ore deposits are highly sheared, and show many evidences of hydrothermal alteration and metamorphism at the greenschist and albite-epidote amphibolite facies. The process of steatitization is variable depending upon the composition, and the degree of alteration and metamorphism of the parent rocks. Steatitization can be divided into two processes with or without serpentinization. The parent rocks with serpentinization are serpentinized dunite, serpentinized peridotite and metagabbro, showing the following alteration process; olivine ${\rightarrow}$ serpentine${\rightarrow}$ talc. The rocks without serpentinization are amphibolite and hornblende schist showing the following sequence; hornblende${\rightarrow}$ chlorite${\rightarrow}$ talc. Formation of talc deposits is summarized as following six stages; I) Intrusion of ultramafic rocks, 2) autometamorphism, 3) metamorphism at greenschist and albite-epidote-amphibolite facies, 4) brittle deformation, 5) hydrothermal alteration, 6) purification of low-grade talc by late dyke intrusion.

• Animal Systematics, Evolution and Diversity
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• v.37 no.4
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• pp.273-279
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• 2021

Branchinotogluma segonzaci (Miura and Desbruyères, 1995) occurs in hydrothermal vent fields of the southwestern Pacific Ocean. We morphologically compared B. segonzaci from the North Fiji Basin with the original description from the Lau Basin and a subsequent study of specimens from the Manus Basin. The main characteristics of all B. segonzaci populations were similar having 21 segments, 10 pairs of elytra, cylindrical-shaped anterior lobes, and ventral papillae on segment 12 and ventral lamellae on segments 13-17 in males. However, the specimens from the North Fiji Basin had rounded to sub-renifrom elytra rather than oval in the original description. Additionally, we newly obtained 11 cytochrome oxidase subunit I (COI) DNA barcodes from the North Fiji Basin and Tonga Arc populations and compared them with known COI DNA barcodes of Branchinotogluma species. Thirteen sequences of B. segonzaci showed 0.0-1.07% intraspecific variation and formed two clades in the COI neighbor-joining tree, whereas the interspecific variation among Branchinotogluma species was 8.19-22.4%. The results of this study contribute to biogeographic studies of B. segonzaci and the evolution of polynoid scale worms in chemosynthesis-based ecosystems.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.1
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• pp.12-19
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• 2022

Desalination has the advantage of being easy to supply water resources. However most desalination devices are developed mainly for large plants and it is not common to use desalination system for a small fishing ship. More than 50% of the input fuel energy of the small shipbuilding's engine is wasted without reused in a ship, and it is necessary to improving the fuel efficiency of the small fishing ship. In this study, a desalination device using waste heat from engine of the ships was developed. As results, it was found that if the condensing chamber uses a fan to circulate the water vapor, the freshwater production was up to 40.0% higher, and the freshwater production efficiency was up to 30.1% increased when the fan was operated.

• Resources Recycling
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• v.13 no.3
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• pp.37-42
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• 2004

PVC powder was dehydrochlorinated by hydrothermal reaction at reaction time 0∼5 hr, reaction temperature $200∼250^{\circ}C$ in 0∼2M NaOH solution, and shape and structure of the PVC residue was investigated. The shape of the residue was changed largely according to NaOH concentration. Most of the residue was cohered in the aqueous solution, and many pores less than 10 $\mu\textrm{m}$ were formed on the surface. Dense network structure was well developed inside the residue. On the other hand, the residue in the NaOH solution was not cohered and its shape is roughly spherical. In the IR spectrum of the residue both in water and NaOH solution at $250^{\circ}C$, aromatic rings and absorption peak by C=C double bond were observed. From the results, it was observed that aromatic circle reaction and bridge reaction occured inter and intra molecules.

• Economic and Environmental Geology
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• v.42 no.6
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• pp.609-618
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• 2009

High permeable faults are important geological structures for fluid flow, energy, and solute transport. Therefore, high permeable faults play an important role in the formation of hydrothermal fluid (or hot spring), high heat flow, and hydrothermal ore deposits. We conducted 2-D coupled thermal and hydraulic modeling to examine thermohydraulic behavior in fault zones with various permeabilities and geometric conditions. The results indicate discharge temperature in fault zones increases with increasing fault permeability. In addition, discharge temperature in fault zones is linearly correlated with Peclet number ($R^2=0.98$). If Peclet number is greater than 1, discharge temperature in fault zones can be higher than $32^{\circ}C$. In this case, convection is dominant against conduction for the heat transfer in fault zones.

• Journal of the Mineralogical Society of Korea
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• v.31 no.4
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• pp.307-323
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• 2018

The Inseong Au-Ag and base metal deposit, located in Chungchengbuk-do, Korea, consists of series of quartz veins filling fissures. The deposit occurs in Hwanggangri meta-sediment formation, a lime pebble-bearing phyllite, in the Okcheon Supergroup. Abundant ore minerals in the deposit are pyrite, arsenopyrite, sphalerite, chalcopyrite and galena. The gangue minerals are quartz, calcite and chlorite. Hydrothermal alteration such as chlorization, silicitication, sericitization and carbonitization can be observed around the quartz veins. 4 vein stages can be distinguished based on its paragenetic sequence, vein structure, alteration features and ore minerals. Microthermometry of the fluid inclusion assemblages occur in the veins are conducted to reconstruct a hydrothermal P-T evolution. Fluid inclusions in clean and barren quartz vein in stage 1 have Th of $270{\sim}342^{\circ}C$ and salinity of 1.7~6.4 (NaCl eqiv.) wt%. Euhedral quartz crystal in stage 2 have Th of $108{\sim}350^{\circ}C$ and salinity of 0.5~7.5 wt%. Barren milky quartz vein in stage 3 have Th of $174{\sim}380^{\circ}C$ and salinity of 0.8~7.5 wt%. Calcite vein in stage 4 have Th of $103{\sim}265^{\circ}C$ and salinity of 0.7~6.4 wt%. Calculated paleodepth about 0.5~1.5 km (hydrostatic pressure) indicate epithermal ore-forming condition. Shallow depth but relatively high-T hydrothermal fluids possibly create a steep geothermal gradient, sufficient for base metal precipitation in the Inseong deposit.

• Journal of the Mineralogical Society of Korea
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• v.20 no.3
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• pp.223-229
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• 2007

The mechanism of hydrothermally synthesizing Na-A zeolite from siliceous mudstone at a $Na_2O/SiO_2$ ratio of 0.6, a $SiO_2/Al_2O_3$ 2.0 and a $H_2O/Na_2O$ 119 has been observed by IR, DTA, XRD and SEM. This mudstone is a tertiary periodic sedimentary rock and widely spreads around the Pohang area. In the early hydrothermal synthesis at $80^{\circ}C$ in an autoclave, sodium silicate and sodium aluminate were found to be preferentially reacted to generate Na-A type zeolite. Gibbsite and bayerite were also formed due to the presence of extra aluminum oxide in the feedstock. As reaction time in-creased up to 50 h, residual sodium aluminatewas reacted with siliceous mudstone, causing the Na-A zeolite crystal to grow and the hydroxylsodalite to generate. Therefore, in the $14{\sim}50\;h$ synthetic time, Na-A zeolite and hydroxylsodalite were formed. Also, if reaction time passed over 50 h, a part of the Na-A zeolite was finally redissolved and reacted with hydroxylsodalite to synthesize Na-P zeolite, generating porous surface of Na-A zeolite and disappearing hydroxylsodalite.

• Journal of the Korean Ceramic Society
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• v.51 no.2
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• pp.115-120
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• 2014

Quicklime(CaO) is generally obtained through the calcination of limestone, the main component of which is calcium carbonate($CaCO_3$). Quicklime generates high-temperature heat when reacting with water, forming slaked lime($Ca(OH)_2$). The industrial sectors for limestone are determined by the hydraulic activity of slaked lime, which is obtained by measuring temperature changes during the hydration reaction. Accordingly, this study examined the different crystallographic characteristics of limestone as affected by the geological origins of the regions where the limestones were produced, and how these characteristics affected hydraulic activity. Six limestone samples were collected from the Jecheon and Cheongsong areas and the hydraulic activities were measured in accordance with KS E 3077. The results indicate that limestone produced in the Cheongsong area, recrystallized through metamorphism caused by hydrothermal alteration, hada larger grain size of calcite than that of the Jecheon area, and displays a tendency of changing to marble. Limestone from the Cheonsong area showed more radical reaction in the early stage of hydration compared to that ofthe Jecheon area. In addition, it was revealed that limestone having more impurities like $SiO_2$ have lower hydraulic activity.

• Economic and Environmental Geology
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• v.24 no.3
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• pp.219-226
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• 1991

High quality quartz crystals are grown in 0.5N NaOH + LiOH solution on the seed crystal at $370-395^{\circ}C$ and $1200-1300kg/cm^2$ condition. Growth rates are determined by the crystal thickness grown on the seed crystals with Z(0001) and X($11\bar{2}0$) direction. Relatively high growth rate of Z(0001) direction gradually changes as the temperaure difference (${\Delta}$ Ti) between growth and dissolution zones from 25 to $10^{\circ}C$. The X axis direction is affeced by ${\Delta}$ Ti, and +X($11\bar{2}0$) direction shows a high growth rate than -X($\bar{1}\bar{1}20$) direction. According to the variation with kinds of solutions used, the crystal growth that in NaOH solution is found to be slower than that in $Na_2CO_3$ solution. However, for the case in the NaOH solution mixed with LiOH, it shows a favorable growth rate in terms of grown crystal quality.

• Economic and Environmental Geology
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• v.21 no.3
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• pp.319-329
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• 1988

As a factor which can help to understand the genesis of (mata) sedimentary and/or hydrothermal uranium depisits, an interpretation of the role of organic matter associated with uranium mineralization, was attempted with the literature published up to the end of 1986. Laboratory studies, in which diageneis and metamorphism are artificially simulated, can help to elucidate how uranium with particular organic materials are formed and destroyed. Similarly, research involving a variety of techniques is needed to characterize both the soluble organic extracts (bitumen) and the insoluble organic matter (kerogen), separated from uranium ores and associated rocks. In the presence of clay minerals and amorphous oxy-hydroxde minerals, an understanding of the role of organic matter must be prudent and may require the incorporation of multidisciplinary approach (mineralogy, inorganic geochemistry ...).